Method of mediating print head cold end temperature during extrusion-based additive construction

ABSTRACT

A carriageless print head assembly, for use in extrusion-based additive construction is disclosed. The carriageless print head features a cold end equipped with one or more timing belt attachment slots and bores for receiving bearings to achieve linear motion. The carriageless print head may be optionally equipped with some combination of an air conduit for cooling the top layer of the constructed product, a fluid channel for aiding in the regulation of the temperature of the print head cold end, and a thermal monitor for monitoring the temperature of the cold end of the print head. A computer-mediated method of monitoring the cold end of the print head to limit jams due to overheating is also disclosed.

CLAIM OF PRIORITY

This application is a divisional of U.S. patent application Ser. No.15/694,772, filed with the United States Patent and Trademark Office onSep. 2, 2017, entitled “Carriageless Print Head Assembly forExtrusion-Based Additive Construction,” the contents of which are herebyincorporated by reference in entirety.

NOTICE OF COPYRIGHTS AND TRADE DRESS

A portion of the disclosure of this patent document contains materialwhich is subject to copyright or trade dress protection. This patentdocument may show and/or describe matter that is or may become tradedress of the owner. The copyright and trade dress owner has no objectionto the facsimile reproduction by anyone of the patent disclosure, as itappears in the Patent and Trademark Office patent files or records, butotherwise reserves all copyright and trade dress rights whatsoever.

FIELD OF THE EMBODIMENTS

The present disclosure relates generally to a carriageless print headfor use in extrusion-based additive construction. More particularly, thepresent disclosure relates to a carriageless print head which can beoptionally configured to have cold end temperature monitoring, liquidcooling of the print head, and/or an air conduit for cooling the toplayer of the final product as it is being printed.

BACKGROUND

In an extrusion-based additive construction (“EAC”) 3D printer, adesired object is formed by melting a continuous solid material feed andselectively depositing the object layer-by-layer onto a flat surface.The defining factors in the quality and reliability of a 3D printer arethe engineering and build quality of a 3D printer's material feeding,melting, and layer deposition mechanics.

EAC 3D printer material feeding, melting, and layer deposition mechanicscan be broken down into two main components: the extruder; and the printhead. The extruder is responsible for the motion of the continuous solidmaterial feed, therefore controlling the amount and rate of which thematerial feed is deposited onto the flat surface, often called a “buildplatform.” The print head is responsible for accepting the material feedpushed into it by the extruder, and subsequently melting it to bedeposited onto a flat build surface. For this reason, the print head isthe only component of the material feeding, melting, and layerdeposition mechanics that must be in motion relative to the EAC 3Dprinter in order to form the desired object.

Despite this truth, many existing EAC 3D printers mount the extruderdirectly above the print head, resulting in the entire assembly movingduring the EAC. While this has some limited benefit when a printedobject is required to be flexible, it has a massive detriment ofmeaningfully limiting the speed with which the extruder/print headcombination can create objects. Additionally, this bulky and heavycombination reduces the size efficiency of the printer, which is definedas the ratio of maximum printed-object size to the size of the printer'schassis.

The fundamental principles behind the extruder and the print head havenot changed much since their inception. The print head can be brokendown into two halves that work in tandem to create the ideal environmentfor EAC: a “hot end” and a “cold end.” Specifically, those componentscreate an optimized structure for feeding a continuous solid materialfeed into a melt zone, so that the melted material feed can besubsequently deposited onto a surface.

The hot end provides the “melt zone” and typically consists of a nozzle,a metal block, a heater cartridge, a temperature sensor, and a heatbreak. That is, the hot end provides the heat necessary to melt thematerial feed such that it may be used in EAC. The temperature sensor istypically either a thermistor or thermocouple. The heat break serves asa connection point from the hot end to the cold end and also providesfor a heat transfer choke point due to its particular mechanical shape.

The purpose of the cold end is to maintain the rigidity of the materialfeed. Since the material feed is being pushed into the hot end, itsrigidity must be maintained else one risks a failure to move it into thehot end due to an inability to “push-on-a-rope.” The hot end and coldend may be collectively referred to as a “print head” though typicallythe print head for an EAC 3D printer contains several additionalcomponents to aid in the printing process though they are not essential.Firstly, the print head is typically fastened to a carriage thatcontains linear bearings (typically ball bearings) in order to achievelinear motion. The carriage also typically contains mount points fortiming belts such that motion can be achieved by off-board motors.

Additionally, the print head may also include an additional fan and fanduct to facilitate the cooling of the top-most layer of the object beingconstructed. This is beneficial because plastic that has not yet cooledprovides a poor foundation for subsequent layers of the print. Withoutproper top layer cooling, an EAC 3D printer can only print at a finitespeed, well below the capabilities of the other components.Additionally, cooling the newly-extruded plastic also increases the‘bridging’ performance of the printer. This means that with additionalcooling of newly-extruded plastic, features with steep overhangs orunsupported spans of plastic may be better achieved.

In the vast majority of existing EAC 3D printers, the cold end of theprint head is air-cooled by radiating heat absorbed into the surroundingenvironment, typically via active cooling with fans and heatsinks andonly in extreme cost-cutting edge cases, passive radiation. In theconstruction of an air-cooled embodiment, there is typically oneheatsink, one pair of standoffs, one axial fan, and one fan blade guardper hot end of the EAC 3D printer. Therefore, for most EAC 3D printerswith two hot ends, there are two heatsinks, two pairs of standoffs, twoaxial fans, and two fan blade guards, in addition to the bolts to fastenthe assembly. This large bill of materials for just the coolingsubcomponent of the EAC 3D print head is expensive to construct and isan inefficient use of space.

While the weight and bill of materials (BoM) savings of apassively-cooled EAC 3D print head is tempting, print heads typicallyinclude some sort of cooling method to keep the cold end cool for afundamental reason. Over enough time, the cold end will begin to absorbheat from the hot end due to heat diffusion. This can lead tocatastrophic failures of the EAC 3D printer as this heat creep couldcause a jam by heating the material feed to its Glass TransitionTemperature (Tg), (the temperature region where the polymer transitionsfrom a hard, glassy material to a soft, rubbery material) thus causing a“pushing-on-a-rope” situation and a subsequent jam.

There have been several attempts in the prior art to improve certaincomponents of an EAC 3D printer print head. However, these componentslack novel features disclosed herein and have yet to be proposed in theunique combination disclosed herein, which yields unexpectedly positiveresults in both weight reduction, size footprint reduction, andreliability while simultaneously achieving all goals already achieved byincumbent design.

The pursuit to reduce EAC 3D printer print head weight is beneficial ascurrently it serves as a bottleneck in the EAC process common to alltypes of EAC 3D printers. Put simply, even minor reductions to theweight of the print head yield meaningful improvements in the speed ofEAC, so major reductions in weight will result in substantialimprovement over the prior art. This is because of the first law ofNewtonian physics that governs inertia: an EAC 3D printer print head inmotion will take significant force to accelerate or decelerateaccurately. Because of this, in order to achieve accurate parts EAC 3Dprinters are programmed to print slower than their theoretical limit.Additionally, the forces from acceleration and deceleration are absorbedby the printer's chassis, linear shafts, and belts, which causevibrations. These vibrations show in completed objects and presentthemselves as surface artifacts in the print. Such surface features makeEAC 3D printing undesirable for cosmetic or end-use parts, but this canbe solved through superior print head design.

As such, there is a need for a print head that is capable ofincorporating all of the desired optional features currently employed inthe art, but has a smaller footprint and weighs less than the printheads known in the art.

SUMMARY

An aspect of an example embodiment in the present disclosure is toprovide a carriageless print head for use in EAC 3D printing.Accordingly, the present disclosure describes a carriageless print headassembly, for use in extrusion-based additive construction, having acold end and a hot end. The cold end has a front end, a rear end, a leftside, a right side, a top surface extending from the front end to therear end and from the left side to the right side, and a bottom surfaceextending from the front end to the rear end and from the left side tothe right side. The hot end is attached to the bottom surface of thecold end, and is preferably removably attached. Preferably, the leftside has a first timing belt attachment slot adjacent to and alignedwith a first receiver for receiving a first shaft, where the firsttiming belt attachment slot extends substantially from the front end tothe rear end, and the first shaft extends substantially from the frontend to the rear end. Also, preferably, the right side has a secondtiming belt attachment slot adjacent to and aligned with a secondreceiver, where the second timing belt attachment slot extendssubstantially from the front end to the rear end, and the second shaftextends substantially from the front end to the rear end. In someembodiments, glide pads are used to facilitate movement along theshafts. In some embodiments, the carriageless print head only interfaceswith a single shaft and only has one pair of the first timing beltattachment slot/first receiver or the second timing belt attachmentslot/second receiver; as opposed to the dual-paired variant discussedabove. The top surface is equipped with a first slot which extendsdownwardly towards the bottom surface and which is configured to receivea material feed.

In some embodiments, the top surface also has a second slot whichextends downwardly towards the bottom surface and is configured toreceive a second material feed. In other embodiments, the carriagelessprint head is equipped with a first heat break and optionally a secondheat break. The first heat break is proximate to the first slot, and thesecond heat break is proximate to the second slot, such that it mayaffect the heat transfer between the cold end and the hot end at thefirst and second slot, respectively.

In other embodiments, the cold end of the carriageless print head isequipped with an air conduit that extends downwardly from the topsurface to the bottom surface. Preferably, the air conduit comprises anipple that extends upwardly from the top surface, and air duct thatextends from the top surface towards the bottom surface. The nipple andair duct are fluidly connected such that air, or some other fluid, maybe passed through the nipple into the air duct. In a highly preferredembodiment, the air duct is equipped with a plurality of fins configuredto optimize airflow from the nipple to the bottom surface. In someembodiments, the air conduit is removably attached to the cold end.

In another preferred embodiment, the top surface also features a thirdslot which extends downwardly towards the bottom surface and isconfigured to receive a cooling fluid, as well as a fourth slot whichextends downwardly towards the bottom surface and is configured to expela cooling fluid. Preferably, the cold end also includes a fluid channelwhich has a perimeter contained within the cold end. There exist manyembodiments where the fluid channel intersects with and extends betweenthe third slot and the fourth slot. In some embodiments, the fluidchannel features an opening on either the left side or right side, anduses a fluid channel plug to seal fluid within the fluid channel. In ahighly preferred embodiment, the perimeter of the fluid channel isbounded by the bottom surface, the top surface, the front end, the rearend, the first receiver, and the second receiver.

In some embodiments, the carriageless print head features a thermalmonitor for monitoring the temperature, preferably the interiortemperature, of the cold end as is experienced by the hot end heatbreak(s), which is located proximate to the cold end to achieve suchmonitoring. The thermal monitor may be a temperature sensor such as athermistor or thermocouple.

The present disclosure also provides for a computer-mediated method ofperforming extrusion-based additive construction while monitoring thecold end, using a 3D printer equipped with the carriageless print headof claim 1, comprising the steps of first beginning an extrusion-basedadditive construction by the 3D printer; reading an operatingtemperature of the cold end interior, by the thermal monitor; assessingwhether the operating temperature is above a predetermined temperaturethreshold; and pausing the construction thus allowing the cold end tocool. In some embodiments, after the printing has been paused, thecomputer then reassesses whether the operating temperature is above thepredetermined temperature threshold. If so, the computer shall keep theprinting paused and will continually reassess the cold end temperature.Optionally, the computer can assess the cold end temperature onpredetermined intervals. Once the cold end is below the thresholdtemperature, printing will resume. In some embodiments, a human operatorwill manually resume printing after they determine that the cold end issufficiently cold.

One benefit of the embodiments in the present disclosure is that EAC 3Dprinters are able to print larger objects for a given printer size whilesimultaneously operating at a faster speed with greater reliability. Toachieve the goal of larger objects and faster speed, this methodstrategically either integrates or off-boards key features of an EACprint head in order to deliver similar or enhanced functionality in areduced size and weight footprint.

First and foremost, through the use of engineered plastic polymerbearings and by integrating the retention for these bearings into theprint head design, the need for a carriage with traditional bearings toachieve linear motion is eliminated. Second, by off-boarding the airsource to cool the top layer of extruded plastic and optionallyintegrating the airflow duct into the print head itself, weight and sizefootprint of the print head is further reduced. In a preferredembodiment, cooling fluid passing through the print head absorbs heat,but its dissipation to the greater environment is handled by anoff-board pump and optional radiator, reservoir, and fan mountedexternally to the moving print head, thereby reducing its size footprintand inertial mass. Further, many embodiments employ press-fitquick-release fittings for the material feed tubes, as well as thecooling fluid inlets and outlets, as well as for connections to thenipple. Finally, many embodiments deploy an additional temperaturesensor in the “cold end” portion of the print head to boost reliability.By monitoring the temperature of the “cold end” of the print head, themethod of the present disclosure can pause printing to allow the printhead cold end to cool down, thereby preventing damage or jams and theirsubsequent print failures from unmonitored heat absorption into theprint head cold end. Optionally, the software may automatically resume aprint once sufficient cooling has occurred, resulting in jam protectionwithout human intervention.

Implementations may include one or a combination of any two or more ofthe aforementioned features.

These and other aspects, features, implementations, and advantages canbe expressed as methods, apparatuses, systems, components, programproducts, business methods, and means or steps for performing functions,or some combination thereof.

Other features, aspects, implementations, and advantages will becomeapparent from the descriptions, the drawings, and the claims.

BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the drawings, like elements are depicted by like reference numerals.The drawings are briefly described as follows.

FIGS. 1A-1B show flow charts illustrating the logic of an embodiment ofthe method of cold end thermal monitoring in accordance with the presentdisclosure.

FIGS. 2A-2B show two embodiments of a carriageless EAC 3D printer printhead design with two differing linear motion shaft systems.

FIG. 3 shows an alternative embodiment of an EAC 3D printer print headdesign whereby linear motion is achieved through a traditional bolt-oncarriage.

FIGS. 4A-4C show various implementations of a top layer cooling featurewith the source of air off-board with respect to the print head.

FIGS. 5A-5C show various implementations of a cold end cooling featurewith the components to dissipate heat to the outside environmentoff-board with respect to the print head.

The present disclosure now will be described more fully hereinafter withreference to the accompanying drawings, which show various exampleembodiments. However, the present disclosure may be embodied in manydifferent forms and should not be construed as limited to the exampleembodiments set forth herein. Rather, these example embodiments areprovided so that the present disclosure is thorough, complete, and fullyconveys the scope of the present disclosure to those skilled in the art.In fact, it will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the scope or spirit of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIGS. 1A and 1B, preferably, the carriageless print head100 is integrated with an embedded thermal monitor 400. In someembodiments, the carriageless print head 100 is integrated with multiplethermal monitors 400. By embedding the temperature sensor 404 in the topsurface 102E, one now has a dedicated thermal monitor 400 that cantrigger protective action to prevent a jam or other damage to thecarriageless print head 100 typically caused by long print jobs or timesof peak printer usage with little rest between jobs.

It is important to note that the presence of the thermal monitor 400alone is insufficient to prevent jams or damage caused by heat creepinto the cold end. For preventative/protective action to be taken,accompanying software must be able to interpret the data provided by thetemperature sensor and trigger action accordingly. Two proposedworkflows for this process are shown in FIGS. 1A and 1B.

“Cold Pause Mode” is defined as a mode in which an EAC 3D printer pausesprinting and disables the heaters in the hot end. This allows theprinter to cool safely and subsequently resume printing without anydamage or risk of completion to the printed object. The process shown inFIG. 1A, is optimal for having printers print continuously, pausing onlyto prevent heat-related jamming or damage. The process shown in FIG. 1Btakes a more conservative approach in that upon detection of too muchheat being absorbed into the cold end, the printer is put indefinitelyinto Cold Pause Mode until a human operator can diagnose the problem andmanually re-engage the printer to complete the print or to cancel theprint job entirely. The workflows disclosed in FIGS. 1A and 1B mayoptionally have an alerting system to notify administrators of theprinters of the detected elevated temperatures in the cold end 102. Itis also notable that while this logic may be embedded into the printer'smain firmware logic, it may also be present on an external logic board.An external logic board would be beneficial when the logic needs to beparsed by such an independent microcontroller and only a stop/pause/coldpause signal can be sent and accepted by the EAC 3D printer's primarycontroller board.

Referring to FIG. 1A, a method of monitoring the temperature of a coldend of an EAC 3D printer 700 is shown. Here, the method 700 begins withstep 702, and proceeds to step 704 where the temperature of a thermalmonitor configured to measure the temperature of the cold is read. Thenthe method 700 proceeds to step 706 where the method 700 assesseswhether the read temperature is above a cold pause threshold. If theread temperature is below the cold pause threshold, the method proceedsto step 720 where the EAC 3D printer is allowed to continue printing.However, if the read temperature is above the cold pause threshold, themethod proceeds to step 708, where the EAC 3D printer enters a coldpause mode, where the print job is stopped. From there, the method 700proceeds to step 710 where the temperature of the thermal monitor isreassessed, and in step 712 the method 700 determines if the readtemperature is still above the cold pause threshold. If so, the methodproceeds to step 716 where printing is paused, and repeats step 710again. If not, the method proceeds to step 714 where the EAC 3D printeris allowed to resume printing.

In FIG. 1A, there are two threshold variables that need to be known: theCold Pause Threshold and the Resume Print Threshold. The Cold PauseThreshold variable is dependent on the material being printed,specifically the material's Glass Transition Temperature (Tg). In someembodiments the Cold Pause Threshold would be equivalent to thematerial's Glass Transition Temperature (Tg), though in other, preferredembodiments, the Cold Pause Threshold should include some buffer toprotect against imperfections in the sensor, or other real-worldenvironmental variables. As an example, when printing in AcrylonitrileButadiene Styrene (ABS) plastic, whose Glass Transition Temperature (Tg)is ˜105 degrees Celsius, an appropriate Cold Pause Threshold could be100 degrees Celsius, giving 5 degrees “buffer”. To resume printing,there would also be a Resume Print Threshold.

In many embodiments, it is to cool below the Resume Print Threshold toprevent excessive pausing and re-starting. Therefore, the Resume PrintThreshold would be set to an arbitrary amount below the Cold PauseThreshold. In the example of Acrylonitrile Butadiene Styrene (ABS)plastic with a ˜105 degrees Celsius Glass Transition Temperature (Tg)and a 100 degrees Celsius Cold Pause Threshold, a Resume Print Thresholdcould be 95 degrees Celsius.

In other embodiments, it may be preferential to the operator that aprinter remain paused until a human technician can diagnose the cause ofthe overheating. This use case is illustrated in the logic outlined inFIG. 1B. Here, the method 700 begins with step 702, and proceeds to step704 where the temperature of a thermal monitor configured to measure thetemperature of the cold end 102 is read. Then the method 700 proceeds tostep 706 where the method 700 assesses whether the read temperature isabove a cold pause threshold. If the read temperature is above the coldpause threshold, the method 700 proceeds to step 708 where the EAC 3Dprinter enters a cold pause mode, and then proceeds to step 722 where ahuman operator must manually resume printing. If the read temperature isbelow the cold pause threshold, the method 700 will proceed to step 720where the EAC 3D printer is allowed to keep printing. In FIG. 1B thereis no need to set a separate Resume Print Threshold because upondetecting the EAC 3D printer's print head cold end temperature breachingthe Cold Pause Threshold, the printer is put in an indefinite ColdPause.

FIGS. 2A and 2B illustrate two embodiments of a carriageless print headin accordance with the present disclosure. Referring to FIG. 2A, acarriageless print head 100 is provided. The carriageless print head 100is comprised of a cold end 102. The cold end 102 has a front end 102A, arear end 102B, a left side 102C, a right side 102D, a top surface 102E,and a bottom surface 102F. The top surface 102E constitutes the topsurface of the cold end 102, and the bottom surface 102F constitutes thebottom surface of the cold end 102, where both the top surface 102E andthe bottom surface 102F extend from the first side 102C to the rightside 102D, and from the front end 102A to the rear end 102B.

Here, the top surface 102E is equipped with a first slot 116A and asecond slot 116B. Both the first slot 116A and the second slot 116B areconfigured to receive a material feed to be used in the EAC process.Preferably, the first slot 116A and the second slot 116B are press-fitquick release plungers, although other types of attachment mechanismsare suitable. Optionally, the top surface 102E is equipped with a cablepassthrough 120, which extends downwardly towards and through the bottomsurface 102F, such that a cable may be threaded through the cold end102. In some preferred embodiments, the top surface 102E features a borefor thermal monitor 118 meant to receive a thermal monitor 400. Thethermal monitor 400 consists of at least one wire 402 and a temperaturesensor 404. The temperature sensor 404 may be a thermocouple,thermistor, or any other type of electronic temperature-sensing devicethat may be interpreted by a microcontroller or similar computingdevice.

Preferably, the left side 102C and the right side 102D are substantiallysymmetrical. The left side 102C is equipped with a first receiver 112Aand a first timing belt attachment slot 110A, and the right side 102D isequipped with a second receiver 112B and a second timing belt attachmentslot 110B. By incorporating the first receiver 112A and the secondreceiver 112B into the cold end 102, a good deal of space, weight, andmechanical complexity is avoided when compared with solutions that existin the prior art. Specifically, the first receiver 112A and secondreceiver 112B replace traditional ball bearings which provides for,greater design freedom. In some embodiments, the second receiver 112B isnot present and only a single shaft is required to operate thecarriageless print head 100. Thanks to this arrangement, bearings nowtake very little space outside of the size of the linear shafts theyslide against, allowing their placement to be within the cold end 102.Optionally, one or more glide pads 150 may be employed to help the firstreceiver 112A and the second receiver 112B slide along a given shaft.Due to the proximate nature of the first receiver 112A and the firsttiming belt attachment slot 110A, as well as the proximity between thesecond receiver 112B and the second timing belt attachment slot 112Aallows the carriageless print head 100 to be propelled along one or morelinear shafts inserted in the first receiver 112A and/or the secondreceiver 112B. Preferably, the first timing belt attachment slot 110Aand the second timing belt attachment slot 110B will be placed along thecenterline of the first receiver 112A and the second receiver 112B,respectively. This has the benefit of minimizing torque during highacceleration of the carriageless print head 100. By using cylindricalshafts, the overall cost of the 3D printer may be reduced via thereduced cost of procuring the commonly used cylindrical shaft.

As shown in FIG. 2B, the first receiver 112A and the second receiver112B may be shaped to work with non-cylindrical shafts. As anon-limiting example, the embodiment shown in FIG. 2B shows the firstreceiver 112A and the second receiver 112B in a configuration to use aT-shaped shaft. Here the optional glide pads 150 are shaped to interfacewith the T-shaped shaft as well as the first receiver 112A and thesecond receiver 112B. T-shaped shafts are desirable because they offer abalance between weight savings and maximum unsupported span. Forlarge-format EAC 3D printers, the length of the linear shafts to spantheir large build platforms poses an engineering problem:larger-diameter shafts add weight to a system in motion, butsmaller-diameter shafts cannot support the weight of an EAC print headwithout significant deflection-hindering the ability to print at verysmall layer heights and introducing potential for resonant frequenciesthat impact print quality. Accordingly, the embodiment of FIG. 2B couldbe deployed in a large-scale EAC 3D printer and exhibit significantweight savings, therefore achieving the goal of faster print speeds andbetter printed-part-to-printer-size ratio, with the unexpected outcomeof reduced mechanical complexity in assembly of the EAC 3D printer printhead prior to installation in the EAC 3D printer. Many othercross-sectional shapes of linear shafts are compatible with the firstreceiver 112A and the second receiver 112B, the first receiver 112A andthe second receiver 112B just need to be shaped complimentarily to thedesired shaft. In some embodiments, one or more glide pads 150 areinserted at the interface of the first receiver 112A and the firstshaft, as well as the interface between the second receiver 112B and thesecond shaft. Again, in some embodiments only the first receiver 112A ispresent and the carriageless print head 100 operates using a singleshaft.

Referring to FIG. 3, an embodiment of the print head 100 is shownwithout the first receiver 112A or the second receiver 112B, and isinstead depicted with a traditional carriage 160. As can be seen, theuse of a separate carriage 160 to achieve linear motion requiresadditional mechanical complexity in assembly of the final product. Inthis embodiment, the use of the carriage 160 prevents meaningful weightsavings, and size savings, offered by the embodiments shown in FIGS. 2Aand 2B.

FIGS. 4A-4C show various embodiments of an air conduit 200 in accordancewith the present disclosure. In FIG. 4A, the air conduit 200 consists ofa nipple 202, and an air duct 204. In this embodiment, the air duct 204is removably attached to the cold end 102. The nipple 202 allows thesource of the air to be located somewhere not on the cold end 102,allowing for meaningful size and weight reduction of the carriagelessprint head 100.

Typically, in devices known in the prior art, air sources employed inEAC 3D printing use an air source that is mounted on the given printhead in motion. These air sources may be either radial fans or axialfans, and may also have an air duct to direct airflow downwards towardsnewly-extruded plastic in order to avoid cooling the hot end. Thesedesigns all bear the flaw of having the moving mass of the air sourceand any optional duct on the print head, which increases its size,reduces its speed due to its mass, and potentially has an impact onprint quality due to resonant frequencies due to inertial mass.

In contrast, the embodiments shown in FIGS. 4A-4C employ variousoff-board air sources for cooling the top layer of a printed object. Thenipple 202 preferably connects to an off-board air source via abarbed-tube fitting, but could employ a compression fitting,push-to-connect tube fitting, or other known mechanical fastening agentsfor tubes that supply pressurized airflow. The external air source maybe an air compressor, compressed air (or other pressurized gas) tank,chemical reaction, motorized bellows, or even a fan capable of drivingsufficient pressure through a small-diameter tube.

Referring to FIG. 4B, the air conduit 200 is shown in an integratedembodiment. That is, the air conduit 200 has been integrated into thecold end 102. This achieves the goal of having an off-board air sourceprovide cooling air to the top layer. FIG. 4C shows a highly preferredembodiment where the air conduit 200 is integrated with the cold end102, but is also equipped with a plurality of embedded fins 206 and theair duct 204 is optimized to facilitate airflow therethrough. Theplurality of embedded fins 206 create a uniform-velocity flow at theexit orifice, effectively creating a ‘blade of air’ to cool the toplayer of the printed part. This provides optimal performance to preventover or under-cooling localities of the printed part. The embodiment ofthe air conduit 200 shown in FIG. 4C is also optimal in its placement ofthe air duct 204: by situating the air conduit 200 between the firstslot 116A and the second slot 116B, the air duct 204 coolsnewly-extruded filament material just as effectively regardless ofwhether the first slot 116A or the second slot 116B is extruding thematerial feed.

Referring to FIGS. 5A-5C, three embodiments of a water channel 300 or acooling fluid channel 300 are shown. In these embodiments, the cold end102 is cooled by liquid cooling. FIG. 5A shows the water channel 300 isdrilled from either the left side 102C or the right side 102D andsubsequently plugged with cooling fluid channel plug 302 to form a seal.Such a seal may take many forms, such as a set screw, a set screw withthread lock, other screw-type plugs, and deformable metal coolingcircuit plugs. Cooling fluid, preferably water, is circulated throughthe third slot 114A and the fourth slot 114B, which are configured toallow fluid to selectively pass through them.

FIG. 5B shows an embodiment where the cooling fluid channel 300 iscompletely contained within the cold end 102. This embodiment providesbenefits over the one shown in FIG. 5A because there is nopost-manufacture assembly required to seal the cooling fluid channel,correspondingly no failure point for the cooling fluid channel's seal,and lastly offers the greatest amount of design freedom.

Shown in FIG. 5C is a highly preferred embodiment in accordance with thepresent disclosure. This embodiment depicts a cooling fluid channel 300with a perimeter 304 where the connection between the third slot 114Aand the fourth slot 114B is not a simple channel, but rather where theperimeter 304 constitutes a completely customized internal envelopewithin the cold end 102. In FIG. 5C we see that there is not only achannel to connect the fluid inputs and fluid outputs, but this channelis expanded to envelop other features internal to the carriageless printhead 100. By doing this, one no longer has to rely on the thermalconductivity of the cold end 102.

It is understood that when an element is referred hereinabove as being“on” another element, it can be directly on the other element orintervening elements may be present therebetween. In contrast, when anelement is referred to as being “directly on” another element, there areno intervening elements present.

Moreover, any components or materials can be formed from a same,structurally continuous piece or separately fabricated and connected.

It is further understood that, although ordinal terms, such as, “first,”“second,” “third,” are used herein to describe various elements,components, regions, layers and/or sections, these elements, components,regions, layers and/or sections should not be limited by these terms.These terms are only used to distinguish one element, component, region,layer and/or section from another element, component, region, layerand/or section. Thus, “a first element,” “component,” “region,” “layer”and/or “section” discussed below could be termed a second element,component, region, layer and/or section without departing from theteachings herein.

Features illustrated or described as part of one embodiment can be usedwith another embodiment and such variations come within the scope of theappended claims and their equivalents.

Spatially relative terms, such as “beneath,” “below,” “lower,” “above,”“upper” and the like, are used herein for ease of description todescribe one element or feature's relationship to another element(s) orfeature(s) as illustrated in the figures. It is understood that thespatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the figures. For example, if the device in thefigures is turned over, elements described as “below” or “beneath” otherelements or features would then be oriented “above” the other elementsor features. Thus, the example term “below” can encompass both anorientation of above and below. The device can be otherwise oriented(rotated 90 degrees or at other orientations) and the spatially relativedescriptors used herein interpreted accordingly.

Example embodiments are described herein with reference to cross sectionillustrations that are schematic illustrations of idealized embodiments.As such, variations from the shapes of the illustrations as a result,for example, of manufacturing techniques and/or tolerances, are to beexpected. Thus, example embodiments described herein should not beconstrued as limited to the particular shapes of regions as illustratedherein, but are to include deviations in shapes that result, forexample, from manufacturing. For example, a region illustrated ordescribed as flat may, typically, have rough and/or nonlinear features.Moreover, sharp angles that are illustrated may be rounded. Thus, theregions illustrated in the figures are schematic in nature and theirshapes are not intended to illustrate the precise shape of a region andare not intended to limit the scope of the present claims.

Attention is called to the fact, however, that the drawings areillustrative only. Variations are contemplated as being part of thedisclosure.

In the present disclosure, where a document, act or item of knowledge isreferred to or discussed, this reference or discussion is not anadmission that the document, act or item of knowledge or any combinationthereof was at the priority date, publicly available, known to thepublic, part of common general knowledge or otherwise constitutes priorart under the applicable statutory provisions; or is known to berelevant to an attempt to solve any problem with which the presentdisclosure is concerned.

While certain aspects of conventional technologies have been discussedto facilitate the present disclosure, no technical aspects aredisclaimed and it is contemplated that the claims may encompass one ormore of the conventional technical aspects discussed herein.

The invention is described above with reference to block and flowdiagrams of systems, methods, apparatuses, and/or computer programproducts according to exemplary embodiments of the invention. It will beunderstood that one or more blocks of the block diagrams and flowdiagrams, and combinations of blocks in the block diagrams and flowdiagrams, respectively, can be implemented by computer-executableprogram instructions. Likewise, some blocks of the block diagrams andflow diagrams may not necessarily need to be performed in the orderpresented, or may not necessarily need to be performed at all, accordingto some embodiments of the invention.

These computer-executable program instructions may be loaded onto ageneral-purpose computer, a special-purpose computer, a processor, orother programmable data processing apparatus to produce a particularmachine, such that the instructions that execute on the computer,processor, or other programmable data processing apparatus create meansfor implementing one or more functions specified in the flow diagramblock or blocks. These computer program instructions may also be storedin a computer-readable memory that can direct a computer or otherprogrammable data processing apparatus to function in a particularmanner, such that the instructions stored in the computer-readablememory produce an article of manufacture including instruction meansthat implement one or more functions specified in the flow diagram blockor blocks. As an example, embodiments of the invention may provide for acomputer program product, comprising a computer-usable medium having acomputer-readable program code or program instructions embodied therein,said computer-readable program code adapted to be executed to implementone or more functions specified in the flow diagram block or blocks. Thecomputer program instructions may also be loaded onto a computer orother programmable data processing apparatus to cause a series ofoperational elements or steps to be performed on the computer or otherprogrammable apparatus to produce a computer-implemented process suchthat the instructions that execute on the computer or other programmableapparatus provide elements or steps for implementing the functionsspecified in the flow diagram block or blocks.

Accordingly, blocks of the block diagrams and flow diagrams supportcombinations of means for performing the specified functions,combinations of elements or steps for performing the specified functionsand program instruction means for performing the specified functions. Itwill also be understood that each block of the block diagrams and flowdiagrams, and combinations of blocks in the block diagrams and flowdiagrams, can be implemented by special-purpose, hardware-based computersystems that perform the specified functions, elements or steps, orcombinations of special purpose hardware and computer instructions.

As the invention has been described in connection with what is presentlyconsidered to be the most practical and various embodiments, it is to beunderstood that the invention is not to be limited to the disclosedembodiments, but on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the scope ofthe appended claims. Although specific terms are employed herein, theyare used in a generic and descriptive sense only and not for purposes oflimitation.

This written description uses examples to disclose the invention,including the best mode, and also to enable any person skilled in theart to practice the invention, including making and using any devices orsystems and performing any incorporated methods. The patentable scope ofthe invention is defined in the claims, and may include other examplesthat occur to those skilled in the art. Such other examples are intendedto be within the scope of the claims if they have structural elementsthat do not differ from the literal language of the claims, or if theyinclude equivalent structural elements with insubstantial differencesfrom the literal language of the claims.

In conclusion, herein is presented a carriageless print head. Thedisclosure is illustrated by example in the drawing figures, andthroughout the written description. It should be understood thatnumerous variations are possible, while adhering to the inventiveconcept and spirit of the invention. Such variations are contemplated asbeing a part of the present disclosure.

What is claimed is:
 1. A method of performing extrusion-based additiveconstruction using a 3D printer equipped with a print head and acontroller, the print head comprising a hot end, a cold end, and athermal monitor, the thermal monitor comprising a temperature sensor,the method comprising the steps of: a. beginning, by the 3D printer, anextrusion-based additive construction; b. reading, by the temperaturesensor, an operating temperature of the cold end; c. assessing, by thecontroller, whether the operating temperature is above a predeterminedtemperature threshold; d. pausing, by the controller, the constructionfor a predetermined amount of time and allowing the cold end to cool. 2.The method of claim 1, further comprising the steps of e. reassessing,by the controller, whether the operating temperature is above thepredetermined temperature threshold; f. repeating steps d and e untilthe operating temperature is below the predetermined temperaturethreshold; g. resuming, by the 3D printer, the extrusion-based additiveconstruction.
 3. The method of claim 1, further comprising the step of:e. manually resuming, by a human operator, the extrusion-based additiveconstruction.
 4. A method of performing extrusion-based additiveconstruction using a 3D printer equipped with a carriageless print headand a controller, the carriageless print head comprising a hot end, acold end, and a thermal monitor, the thermal monitor comprising atemperature sensor, the method comprising the steps of: a. beginning, bythe 3d printer, an extrusion-based additive construction; b. reading, bythe temperature sensor, an operating temperature of the cold end; c.assessing, by the controller, whether the operating temperature is abovea predetermined temperature threshold; d. pausing, by the controller,the construction for a predetermined amount of time and allowing thecold end to cool.
 5. The method of claim 4, wherein the cold end has afront end, a rear end, a left side, a right side, a top surfaceextending from the front end to the rear end and from the left side tothe right side, and a bottom surface extending from the front end to therear end and from the left side to the right side, wherein the left sidehas a first timing belt attachment slot adjacent to and aligned with afirst receiver for receiving a first shaft, the first timing beltattachment slot extending substantially from the front end to the rearend, the first shaft extending substantially from the front end to therear end, wherein the right side has a second timing belt attachmentslot adjacent to and aligned with a second for receiving a second shaft,the second timing belt attachment slot extending substantially from thefront end to the rear end, the second shaft extending substantially fromthe front end to the rear end, wherein the top surface is equipped witha first slot, a second slot, a third slot, and a fourth slot, the firstslot extending downwardly towards the bottom surface and is configuredto receive material feed, the second slot extending downwardly towardsthe bottom surface and is configured to receive material feed, the thirdslot extending downwardly towards the bottom surface and is configuredto receive a cooling fluid, the fourth slot extending downwardly towardsthe bottom surface and is configured to expel a cooling fluid, whereinthe carriageless print head is equipped with a first heat break, whichis proximate to the first slot and a second heat break which isproximate to the second slot, wherein the cold end is of a singularconstruction.
 6. The method of claim 5, wherein the thermal monitor islocated within the cold end such that the temperature of the cold endmay be monitored by the thermal monitor.
 7. The method of claim 6, thecarraigeless print head further comprising: an air conduit extendingdownwardly from the top surface to the bottom surface, wherein the airconduit comprises a nipple extending upwardly from the top surface, andair duct extending downwardly from the nipple to the bottom surface, theair duct and the nipple being fluidly connected, wherein the air duct isequipped with a plurality of fins configured to optimize airflow fromthe nipple to the bottom surface; a fluid channel having a perimeter,wherein the perimeter of the fluid channel is contained within the coldend and the perimeter is bounded by the bottom surface, the top surface,the front end, the rear end, the first receiver and the second receiver.8. The method of claim 7, further comprising the steps of h.reassessing, by the controller, whether the operating temperature isabove the predetermined temperature threshold; i. repeating steps d ande until the operating temperature is below the predetermined temperaturethreshold; j. resuming, by the 3d printer, the extrusion-based additiveconstruction.
 9. The method of claim 7, further comprising the step of:f. manually resuming, by a human operator, the extrusion-based additiveconstruction.